46 BULLETIN 1422, U. S. DEPARTMENT OE AGRICULTURE 
naturally, is prevalent along the rivers, but the high areas back from 
the rivers are free from mosquitoes and are surprisingly healthful. 
The great distance from a seaport militates against economical 
production, because all laborers and all supplies for the laborers and 
for the plantation must be carried over this long stretch of water at 
rather high cost. An extensive development of plantations in this 
region would undoubtedly result in an improvement in transporta- 
tion and cause a decided decrease in freight rates. This territory is 
after all so much nearer the rubber-manufacturing centers of tne 
world that there appears to be no good reason why rubber should 
not be marketed from the South American plantations with a lower 
transportation cost than that of the eastern product. Lower freight 
rates on supplies for the plantations should also result in lower pro- 
duction costs than would be possible at present. 
OTHER REGIONS 
Reports have it that there are superior lands on the upper stretches 
of such rivers as the Tocantins, the Tapajos, and the Xingu. If 
these are the equal of the lands already mentioned, they should be 
excellent for rubber planting on account of their accessibility. Their 
proximity to Para would greatly reduce transportation rates and to 
that extent help to reduce production costs. 
TYPES OF HEVEA BRASILIENSIS IN THE AMAZON VALLEY 
There has been considerable confusion about the types of rubber 
trees exploited in the Amazon Valley, particularly in regard to the 
native names applied to them. Mention has been made of the rubber- 
bearing species other than Hevea brasiliensis. Since these are all 
recognized as inferior and of lesser importance in exploitation and of 
no immediate value for planting, there is no need to discuss them 
further. 
It seems to be almost an article of faith with the seringueiro that 
three types of trees exist — seringa branca (white), seringa vermelha 
(red), and seringa preta (black). Various other names are applied 
to other species; in fact, seringa vermelha is most often applied to a 
species other than Hevea hrasiliensis, usually H. collina. In the 
island region and on the lower Amazon the preta tree is rarely seen, 
but the branca and vermelha types are common. Sometimes the 
vermelha is spoken of as rosa; at least no distinction could be made 
between vermelha and rosa except that one man would use one term 
and another the other. 
Both these types of trees are obviously Hevea brasiliensis. The 
only distinction which is used in determining to which type a tree 
belongs appears to be the color of the inner bark. In the branca 
type the inner bark is whitish in color with tan flecks in it. In 
such trees wounding causes the formation of bark which is red in 
color. This is the type of bark which is predominant on the trees 
in the Orient. 
The vermelha trees have red or reddish inner bark, which is other- 
wise quite the same as in the branca type. The distinction between 
the two as usually applied means nothing. A branca tree badly 
chopped with a maehadinho will present red bark over all its lower 
trunk and on superficial examination might be classed by the serin- 
